VW Taigo NOx Sensor Failure & Exhaust Leak Fix Guide

Had the same trouble on a 2019 VW T-Cross with similar symptoms. The check engine light triggered due to a failing NOx sensor, which was causing incorrect air-fuel ratio readings. The exhaust leak sound typically indicates deterioration around the sensor mounting points. The root issue was a combination of corroded wiring harness connections and a damaged plug connector going to the NOx sensor. The exhaust system needed partial disassembly to access and replace the affected components. This repair requires specialized diagnostic equipment to ensure proper pollution control system function after installation. Not a quick fix, the entire job took nearly a full day at the shop. The faulty connections were causing erratic sensor readings, which made the engine run rich and triggered the check engine warning. Would strongly recommend having a VW specialist handle this, as incorrect installation can lead to more serious engine management issues. The exhaust leak noise completely disappeared after repair and the engine returned to normal operation. This is a somewhat common issue on these platforms around the 130000-150000km mark.

Thanks for sharing that experience with the T-Cross. Did you happen to track the total repair cost? Wondering if your fix was just the NOx sensor replacement or if the catalytic converter needed attention too. My Taigo still runs rough when cold and Im worried more components might be affected beyond just the sensor failure. Just had the first error codes read yesterday and trying to budget for what might be ahead. Let me know if youve had any recurring issues since the repair was done. Really hoping to avoid multiple shop visits if possible.

Got my car back from the shop last week actually. The total repair came to 95€, much less than expected since it turned out to be just a faulty cable connection to the NOx sensor. No catalytic converter work needed. The sensor failure was causing those cold start issues you mentioned. The poor connection meant the engine management system wasnt getting accurate air-fuel ratio readings. Since fixing the wiring, cold starts are smooth and the exhaust system is working perfectly. No recurring issues at all after they properly sealed the connections. The emission sensor is now reporting correct values and the check engine light has stayed off. A proper diagnosis really helped avoid unnecessary parts replacement, the sensor itself was actually fine once they fixed the connection. Worth noting that not all rough running issues trace back to the NOx sensor, but given your similar symptoms and mileage, it might be the same straightforward fix. The diagnostic equipment they used pinpointed the exact connection problem quickly.

Just got back from the mechanic and wanted to update. You were spot on about getting proper diagnostics first. My case turned out more complex than yours though. The NOx sensor had completely failed and damaged part of the exhaust system. Total repair came to 780€, they replaced the sensor, fixed a cracked pipe section, and updated the engine management software. The cold start issues are now completely gone and no more exhaust leaks. The mechanic showed me the corroded sensor, it was basically disintegrating. Really glad I didnt wait longer as it could have caused more extensive damage. The check engine light is finally off and the car runs like new again. Thanks for sharing your experience. It helped me ask the right questions at the shop and understand what they were checking for.